We don't go to school _____ Saturdays or Sundays. [ ]
A. at
B. for
C. on
答案：C
My parents _____eat junk food, because it’s bad for our health.
A．often
B．never
C．sometimes
D．Always
动力指数是指（）消耗功率（）所得到的空气量。
A．每分钟；10KW
B．每小时；1KW
C．每小时；10KW
D．每分钟；1KW
